Noun
Originally, in classical architecture, the triangular space forming the gable of a simple roof; hence, a similar form used as a decoration over porticoes, doors, windows, etc.; also, a rounded or broken frontal having a similar position and use. See Temple.
Source: Webster's dictionaryGrandma, he had often wanted to say, Is this where the world began? For surely it had begun in no other than a place like this. The kitchen, without doubt, was the center of creation, all things revolved about it; it was the pediment that sustained the temple. Ray Bradbury
At either end of the building the pediment rises from the cornice, framed by moulding of similar form. Source: Internet
Church façades are generally surmounted by a pediment and organised by a system of pilasters, arches and entablatures. Source: Internet
At either end of the building the gable is finished with a triangular pediment originally filled with sculpture. Source: Internet
A tympanum is the decorated surface of a pediment. Source: Internet
Further alterations were made by Bernini including the façade pediment. Source: Internet